Kafka Message Format

When using the Kafka sink, the pipeline sends one JSON message per frame containing all detected objects:

{
  "version": "1.0",
  "source_id": 0,
  "frame_id": 180,
  "timestamp": "2026-01-29T16:39:38.066Z",
  "objects": [
    {
      "class_id": 0,
      "label": "car",
      "confidence": 0.93,
      "bbox": {
        "left": 384.89,
        "top": 321.08,
        "width": 16.56,
        "height": 16.64
      },
      "tracking_id": 19
    }
  ]
}

Schema

Field	Type	Description
`version`	string	Message schema version (currently `"1.0"`)
`source_id`	integer	Input stream index this frame belongs to
`frame_id`	integer	Frame number since pipeline start
`timestamp`	string	RFC 3339 wall-clock timestamp
`objects`	array	Detected objects in this frame
`objects[].class_id`	integer	Model output class ID
`objects[].label`	string	Class name from the model's label file
`objects[].confidence`	float	Detection confidence (0.0 – 1.0)
`objects[].bbox`	object	Bounding box: `left`, `top`, `width`, `height` (in pixels)
`objects[].tracking_id`	integer	Tracker-assigned ID (`-1` if no tracker is configured)

Schema​

Schema